Robotic Cockroach Can Walk on Land, Swim and Walk Underwater

 A team of researchers at Harvard's John A. Paulson School of Engineering have developed a robotic cockroach that can walk on land, swim on the surface of water and walk underwater. Harvard's Ambulatory Microrobot, known as HAMR, can survive up to 30 minutes underwater.
 To allow the robot to shift from land to water and vice versa, the machine relies on multi functional foot pads that are dependent on surface tension. To allow HAMR to swim, the machine relies on surface tension induced buoyancy while voltage can be applied to break the water surface when HAMR needs to sink. This process is known as electrowetting, which is the reduction of the contact angle between a material and the water surface under an applied voltage.
 Using four pairs of asymmetric flaps and custom designed swimming gaits, HAMR is capable of paddling on the water's surface to swim. To the observer, this robots appear to generate swimming gaits similar to that of a diving beetle.
  “HAMR’s size is key to its performance,” said Neel Doshi, graduate student at SEAS and co-author of the paper, when noting the robot's 1.65 gram weight.  “If it were much bigger, it would be challenging to support the robot with surface tension and if it were much smaller, the robot might not be able to generate enough force to break it.”
Read more about this fascinating story at: https://www.seas.harvard.edu/news/2018/07/next-generation-robotic-cockroach-can-explore-underwater-environments